Dextrose/water/whey by sipping SLOWLY until you compete. I forget why you shouldn't slam it though.

If you HAD to eat a meal, possibly white rice, white pasta or something with a high gi and egg whites with water.

You won't be able to top off your glycogen stores nor will you be fully hydrated no matter what you eat if its only an hour after weigh ins. They try to discourage dropping a lot of weight when your weigh-ins are that close to competing. Good luck.